A cylindrical tank having a structure that includes an inner tank and an outer tank is used to store cryogenic liquids such as LNG (liquefied natural gas) and LPG (liquefied petroleum gas). A method of constructing a cylindrical tank having an inner tank made of metal and an outer tank made of concrete is disclosed in Patent Document 1.
In this method of constructing a cylindrical tank, firstly, a base plate is constructed, and steel liners (i.e., outer tank lateral plates) are then stacked sequentially in layers on top of this base plate and are fixed in position by welding. After the steel liners have been assembled, an outer tank sidewall is constructed by setting up an outer side forming frame, and pouring concrete with the steel liners being used as an inner side forming frame. At the same time, a frame and deck of an outer tank roof are assembled on an inner side bottom portion of the outer tank sidewall, and are then mounted on an apex portion of the outer tank sidewall. Thereafter, the concrete of the outer tank roof is poured and, lastly, the inner tank is assembled. As a result, a cylindrical tank having a function of storing LNG and the like at low temperatures is constructed.